The present invention relates to a printed wiring board and a module for an IC card using the printed wiring board, and more particularly, relates to improvement in reliability of IC cards.
In recent years, for reduction in the size of IC cards and the number of components of an IC card, improvement in flexural strength, cost reduction, and other purposes, a module for an IC card having the following structure has been proposed. A semiconductor device is directly mounted on a printed wiring board of the module and sealed with a resin.
A conventional IC card module will be described with reference to FIGS. 12(a) and 12(b). FIG. 12(a) is a top view of the conventional IC card module, and FIG. 12(b) is a cross-sectional view taken along line Xxe2x80x94X in FIG. 12(a).
A conventional IC card module 110 includes: a substrate 111; a semiconductor device 113 mounted on the substrate 111; terminals 118 formed in the bottom portion of the substrate 111; connection holes (not shown) extending through the substrate 111 to reach the terminals 118; connection lands (not shown) formed on the substrate 111 and connected with the terminals 118 via the connection holes; wires 114 for connecting the connection lands and the semiconductor device 113; and a resin 116 for sealing the semiconductor device 113. The wires 114 are conductive wires made of metal such as gold and aluminum.
The resin 116 sealing the semiconductor device 113 is formed by transfer molding, potting, or printing using a thermosetting resin, or injection molding using a thermoplastic resin.
The IC card module 110 is fitted in a case or the like with the terminals 118 exposed outside, to complete an IC card.
In the conventional IC card module 110, the terminals 118 are located opposite to the semiconductor device 113 with respect to the substrate 111. Therefore, when the IC card is to be connected with an external apparatus provided with an IC card slot, for example, the semiconductor device 113 must be inserted into the slot along with the terminals 118. Therefore, the semiconductor device 113 may possibly be adversely influenced by external mechanical stress, heat from the external apparatus, and the like.
An object of the present invention is to provide a printed wiring board and an IC card module using the printed wiring board that can contribute to improvement in reliability of IC cards.
The IC card module of the present invention includes: a base having a resin sealing region, clamped regions in a periphery zone of the resin sealing region clamped with a sealing mold, and non-clamped regions in the periphery zone of the resin sealing region that are not clamped; a semiconductor device mounted on a top surface of the base; terminals for external connection formed on the top surface of the base; wiring formed on the top surface of the base for connecting the semiconductor device and the terminals; and a resin for sealing the semiconductor device, wherein the terminals are formed in a region other than any of the resin sealing region, the clamped regions, and the non-clamped regions.
The semiconductor device is located at a position apart from the terminals on the base. With this construction, when an IC card fabricated using the IC card module of the invention is to be connected with an external apparatus provided with an IC card slot, the terminals can be inserted into the slot for the connection without placing the semiconductor device inside the slot. This makes it possible to fabricate an IC card having a structure that protects the semiconductor device from being adversely influenced by external mechanical stress, heat from the external apparatus, and the like. That is to say, an IC card with high reliability is obtained.
Preferably, the wiring is formed along routes passing through the non-clamped regions on the top surface of the base.
With the above construction, the wiring is suppressed/prevented from damage due to the clamping with the sealing mold. The resultant IC card module has reduced disconnections and short circuits. In addition, since the wiring is arranged so as to avoid clamping with the sealing mold, the following advantage is obtained in the case of forming a solder resist on the printed wiring board. The surface of the solder resist is waved when it is formed over the wiring. In the region clamped with the sealing mold, however, the solder resist is not waved since no wiring exists in this region. Thus, the resultant IC card module is free from resin leak and has resin sealing with high precision.
The non-clamped regions on the top surface of the base may correspond to a resin injection gate and an air vent of the sealing mold.
Preferably, at least one layer of inner wiring and then an insulating layer are formed on the top surface of the base, the semiconductor device is formed on the insulating layer, and portions of the wiring located in the periphery zone constitute the inner wiring.
With the above construction, the wiring as the inner wiring is sandwiched by and thus mechanically protected by the base and the insulating layer. Specifically, if the IC card module is bent with an external force, the portion that is not sealed with the resin warps, possibly causing damage to the wiring. The inner wiring can reduce such damage due to warping.
A solid pattern is preferably formed on portions of the periphery zone that do not have the wiring.
The above construction can reduce warping in the periphery zone of the resin sealing region, and thus further reduce damage to the wiring and the base.
The top surface of the solid pattern is preferably at a height equal to or greater than the height of a top surface of the wiring.
The above construction prevents the wiring from being clamped with the sealing mold in the periphery zone of the resin sealing region. Therefore, damage to the wiring during the clamping is prevented.
The solid pattern preferably functions as power source wiring or grounding wiring. This stabilizes the voltage from the power supply.
Preferably, the IC card module further includes a semiconductor device formed on a back surface of the base, wiring for connecting the semiconductor device formed on the back surface and the terminals, and a resin for sealing the semiconductor device formed on the back surface.
The above double-sided structure allows for increase in the number of semiconductor devices that can be mounted on the printed wiring board, or decrease in the volume occupied by a semiconductor device when implemented. That is, it is possible to obtain an IC card module with semiconductor devices mounted at a high density.
The printed wiring board of the present invention includes: a base having a resin sealing region, clamped regions in a periphery zone of the resin sealing region clamped with a sealing mold, and non-clamped regions in the periphery zone of the resin sealing region that are not clamped; connection lands formed on the top surface of the base for connection with a semiconductor device; terminals for external connection formed on the top surface of the base; and wiring formed on the top surface of the base for connecting the connection lands and the terminals, wherein the terminals are formed in a region other than any of the resin sealing region, the clamped regions, and the non-clamped regions, and the wiring is formed along routes passing through the non-clamped regions on the top surface of the base.
The above construction suppresses/prevents the wiring from being damaged due to the clamping with the sealing mold. Therefore, an IC card module using the printed wiring board with this construction has reduced disconnections and short circuits. In addition, since the wiring is arranged so as to avoid clamping with the sealing mold, the following advantage is obtained in the case of forming a solder resist on the printed wiring board. In the region clamped with the sealing mold, the solder resist is not waved since no wiring exists in this region. An IC card module using such a printed wiring board is free from resin leak and has resin sealing with high precision.
The non-clamped regions on the top surface of the base may correspond to a resin injection gate and an air vent of the sealing mold.
A solid pattern is preferably formed on portions of the periphery zone that do not have the wiring.
The above construction can reduce warping in the periphery zone of the resin sealing region, and thus further reduce damage to the wiring and the base.
The top surface of the solid pattern is preferably at a height equal to or greater than the height of a top surface of the wiring.
The above construction prevents the wiring from being clamped with the sealing mold in the periphery zone of the resin sealing region. Therefore, damage to the wiring during the clamping is prevented.
Preferably, at least one layer of inner wiring and then an insulating layer are formed on the top surface of the base, the semiconductor device is formed on the insulating layer, and portions of the wiring located in the periphery zone constitute the inner wiring.
With the above construction, the wiring as the inner wiring is sandwiched by and thus mechanically protected by the base and the insulating layer. Specifically, if the printed wiring board is bent with an external force, the portion that is not sealed with the resin warps, possibly causing damage to the wiring. The inner wiring can reduce such damage due to warping.
The method for fabricating an IC card module of the present invention includes the steps of: (a) preparing a printed wiring board comprising: a base having a resin sealing region, clamped regions in a periphery zone of the resin sealing region clamped with a sealing mold, and non-clamped regions in the periphery zone of the resin sealing region that are not clamped; connection lands formed on the top surface of the base for connection with a semiconductor device; terminals for external connection formed on the top surface of the base; and wiring formed on the top surface of the base for connecting the connection lands and the terminals, wherein the terminals are formed in a region other than any of the resin sealing region, the clamped regions, and the non-clamped regions, and the wiring is formed along routes passing through the non-clamped regions on the top surface of the base; (b) mounting the semiconductor device in the resin sealing region by securing the semiconductor device to the base; (c) connecting the semiconductor device and the connection lands by means of conductive members; and (d) clamping the printed wiring board with a sealing mold to seal the semiconductor device with a resin.
By the above method, damage to the wiring due to the clamping with the mold is suppressed/prevented. This makes it possible to obtain an IC card module with reduced disconnections and short circuits.
In the step (a) of preparing a printed wiring board, the non-clamped regions on the top surface of the base may correspond to a resin injection gate and an air vent of the sealing mold.